Attempts to mate him with the two surviving female rhinos failed, however, and an account was created for him on the dating app Tinder last year, not to find love, but to help fund the development of in vitro fertilisation (IVF) for rhinos.

The move won him fans across the world – many of whom were devastated on hearing news of his "ailing condition" last Thursday.

Ol Pejeta's Elodie Sampere, told the BBC the rhino – who is the equivalent of 90 in human years, according to the reserve – had been suffering from bedsores as his mobility decreased, one of which had become infected.

"We are treating his wounds twice a day to avoid the risk of infection and they're getting better," she said on Tuesday. "The sores are being made worse because he lies down too much."

The reserve, which has been caring for Sudan and his two female companions since 2009, keeping them under 24-hour armed guard to protect them from poachers, has accepted the rhino will not be with them much longer.

He had only recovered in the last few months from an infection which took hold late last year.

However, they have been encouraged by Sudan's "lifted spirits" in the last few days.

It’s been raining heavily on Ol Pejeta for the past couple of days and the weather certainly seems to have lifted Sudan’s spirits. He has been able to wallow in the mud – with the careful assistance of his caregivers – something that he seems to savour. pic.twitter.com/B0bhaIL7GN

But conservationists hope this does not mean the end for the northern white rhino. The two female rhinos – Najin and Fatu – are far younger, and progress with IVF may mean they are one day able to have their own calves.